BULLETIN OF THE UNITED STATES FISH COMMISSION. 395 



which they are capable of producing will appear doubtful to those who 

 have seen in the Baltic, besides fish, crabs, and shell-fish, only worms, 

 snails, starfish, and medusae. 



The enormous number of small animals and plants which, at certain 

 times, float about in the water, and the many worms, crustaceans, and 

 shell-fish which densely throng every muddy bottom, can only be ob- 

 served by applying the scientists' implements of investigation — purse- 

 nets with fine meshes, floating-nets, drag-nets, sieves, and magnifying- 

 glasses. Even the sharp eyes of the fishermen cannot see most of those 

 small animals which form the principal food of herring, sprat, mackerel, 

 and flounders. 



It is evident that the fisheries became a disturbing element in the 

 natural co-operation of all the members of the coinniimiiies of living 

 beings in our seas. 



From May, 1879, till the end of February, 1880, the fishermen of 

 Eckernforde, in Schleswig, caught upwards of 1,407,000 golden flounders 

 (Pleuronectes platessa), according to reports made from Eckernforde to 

 the Kiel Commission for the scientific investigation of the German seas. 



We do not know whether this number of fish, if left undisturbed, 

 would have increased still further, or how many eggs they might have 

 laid, if they had not been caught. It is eertaiu, however, that during 

 those ten months the number of golden flounders has been diminished 

 more bv the Eckernforde fishermen than could have been done in the 

 same time by seals and other enemies of these fish or by other causes. 

 And what were the necessary consequences of this decrease? 



(1.) For those flounders which had escaped the fishermen's nets, the 

 removal of so many of their kind had certainly this advantage, that the 

 survivors had more food at their disposal; and as, moreover, those fish 

 which had escaped were, probably, mostly small fish, they would have 

 a still better chance to have plenty to eat, and thus grow faster, than 

 if the additional 1,400,000 flounders would have had to share the food 

 with them. For, large as is the quantity of shell-fish and worms at the 

 bottom of the sea, it has, after all, its limits ; and it certainly will not 

 increase, if the number and the demands of these voracious fish increase. 



(2.) As the 1,400,000 flounders were caught before they had, once 

 more, engaged in the work of propagation, their removal implied the 

 removal of a considerable number of young flounders. 



On the 26th and 27th February, 1883, I bought in the Kiel fish mar- 

 ket five live female flounders, measuring 27 to 36 centimeters in length 

 and weighing 200 to 450 grams. The ovaries of the largest one of these 

 fish weighed 110 grams and only contained immature eggs. By count- 

 ing the eggs of two small, but carefully weighed, portions of these ova- 

 ries, it was found that there were 2,558 to one gram; according to 

 which there would be in the two ovaries 281,380 eggs. As with the 

 other four the eggs were- already flowing from the genital openings, 

 and the ovaries contained large mature and small immature eggs, the 



